Nowadays, numerous trains are based on a Communication-Based Train Control, known as CBTC, in the context of which a CBTC system located onboard the train generates safety-related information about the train. These data are transferred to a ground control station using the communication system of the train which is itself connected to the control station through such an infrastructure.
In a CBTC environment, the communications of the system onboard the train include critical communications, which correspond to the communications for the exchange of the data generated by the CBTC system onboard the train and include for instance information regarding the state of the train such as its speed, its position, surveillance data, etc. In case the critical communication between the train and the control station are interrupted, an emergency stop of the train is triggered.
So as to obtain an overall configuration in which the probabilities of having the transmissions between the onboard systems and the infrastructure fail are minimal, a general approach is to optimize these probabilities for each WRU through an optimized resource allocation scheme to be implemented by the WRU, which for instance takes the form of time-frequency resources being allocated to the various devices the WRU communicates with over a predetermined time window. To that end, the WRU selects a set of orthogonal resources, such as a frequency hopping sequence among a plurality of such sequences, based on a figure of merit designed for the considered WRU and which aims at minimizing the failure probabilities of the devices in communication therewith.